FIG. 1 shows an example of an automobile power supply device in which two batteries can supply electric power to a group of loads. A load group 1 is connected to positive terminals of a first battery 2 and a second battery 3, and is supplied with electric power from at least one of the first battery 2 and the second battery 3. With such a configuration, even if one of the first battery 2 and the second battery 3 fails, the load group 1 is supplied with electric power from the other battery that has not failed, and thus redundancy of the power supply is secured.
In the above-described automobile power supply device, if, for example, the second battery 3 fails and needs to be replaced, connection plugs 6 and 7 are disengaged from connection terminals 4 and 5 of the second battery 3, and the battery that has failed is replaced by a new battery. Even during such a replacement operation, the load group 1 continues to be supplied with electric power from the first battery 2, and can thus perform a normal operation.
Automobile power supply devices may be provided with a power supply wiring for supplying electric power to various loads from batteries, and a connector that is disposed in the power supply wiring. When replacing a battery, an operator disengages the connector prior to disengaging the battery.
Modern automobiles use loads that need a power supply voltage of, for example, 48V that is higher than an ordinary voltage of 12V or 24V, and are provided with a battery for outputting a DC voltage of 48V to supply electric power to the loads. In conventional automobile power supply devices, when a connector is disengaged while electric power is supplied from the battery to the loads, arc discharge may occur between connector terminals that are being separated, and the connector terminals may be broken.
Accordingly, a power supply apparatus has been proposed in which arc discharge is prevented from occurring in the connector by an operator manually disengaging a service plug prior to disengaging a connector so as to interrupt the supply of electric power from a battery to loads. Furthermore, Patent JP 2003-17198A discloses a service plug that can extinguish, within a short time, an arc that occurs when a connection electrode and a shorting member are separated from each other. JP 2013-62043A discloses a locking device that reliably holds a connector in an engaged state using a catching part that elastically engages the connector.
In the example of FIG. 1, during a replacement operation, the connection plug 6 still continues to be supplied with electric power from the first battery 2, and thus if the connection plug 6 is placed in contact with the connection plug 7, a vehicle body, or the like by mistake, a spark may occur in the contact portion or the power supply wiring 8 may burn out, due to an earth fault.
JP 2009-12728A discloses a power supply apparatus that is provided with a battery and a capacitor, and has a configuration in which, in cases of over-discharge of the battery, power supply from the capacitor is interrupted. However, JP 2009-12728A does not disclose a configuration that supplies electric power to a load group during an operation for replacing the battery, while preventing occurrence of a spark or the like that may occur due to an earth fault.
In the power supply apparatus disclosed in JP 2003-17198A, if an operator has forgot to disengage the service plug before the replacement of a battery, and disengages a connector, arc discharge may occur between connector terminals.
It is an object of the present invention to provide an automobile power supply device in which a battery replacement operation can be performed safely.